オーディオ・音響・PCオーディオ・アナログのAurorasound（オーロラサウンド）

PREDA-English

PREDA

PREDA is a solid state preamplifier with analog IN/OUT employing state-of-the-art transformer-type volume control system. The transformer uses super-reliable lead relays with 54-step, permitting precise setting with perfect Infrared remote control. Unlike conventional resister-type attenuator, the transformer system has no loss of signals, as heat, enabling precision volume control settings. Aurorasound’s newly developed discrete amp-module, having achieved ultra wideband and low distortion, balances input signal sources and adopt any type of output power amplifiers with excellent signal control.

PREDA is developed with a completely new concept by adopting independent block for power supply, amplifiers, input and output modules for each L/R channels. A heavy duty solid aluminum chassis, extruded knobs, anti-vibration foot insulators are employed to achieve the highest-level musical performance, operation and aesthetics. It is an ideal preamplifier as the center core of your audio system.

Apr.2014, Gain select switch is added on the bottom of chassis. This function is more minus 16 step down foe mid-night listening.

Supplemental Explanation

Block Diagram

1.Transformer-type Attenuator is an Energy Transfer Device

A conventional resistor-type attenuator waste energy of reduced signal as heat. Since the current in a preamplifier is small, it does not give off high heat, however, attenuated signal is discharged in the air as heat. A transformer-type attenuator is an electric energy convertor without energy loss, therefore, it allows lossless signal level control. A typical transformer-type attenuator has only around 32 steps, but Aurorasound adopted 54 steps, which allows precise setting of volume level.

Transformer-type attenuator is available as a module. There is an issue associated with transformer-type attenuator. When CD Player and/or Power Amplifier having capacitors, which cut DC, are combined with the transformer-type attenuator, it generates a LC resonator causing undesirable impact on frequency response and phase alignment. PREDA eliminated such problems by adopting DC amplifiers before and after the transformer. As a result, it completely eliminates the influence of the capacitors.

2.Highly-reliable Lead Relay is used for tap selection

Highly-reliable lead relay encapsulated in small glass tubes are of UK-based Pickering Manufacture. ON/OFF switching is accomplished by an external magnetic field generated by current in the coil. Multiple lead relays are completely shielded by mu-metal to avoid mutual interferences.

3.Newly Developed Aurora-AMP Module

Aurora-AMP Module is a discrete amplifier, capable of handling heavy load for high driving, up to 110dB open-loop gain. It has 12MHz gain-band width, THD+N of 0.0003%, through-rate of 28V/ usec, offering extremely high performance. The PCB is gold plated, without use of resist proces,s to avoid any coloration on sound. PREDA uses 6 units of this AMP module. This unit has become the core amplifier module of Aurorasound representing our company’s sound philosophy

Aurora-AMP Module

4.Well-recognized power supply in VIDA is also used in PREDA, as well.

This power supply is highly reputable for its super-low noise and high speed. PREDA is equipped with 2 independent power supply units for L/R channels. These power supplies are packaged in series to cancel unnecessary leakage flux from the transformers as shown in the picture below.

L/R Independent Power Supply

5.Balanced Input has Instrumentation Amp Structure

An Instrumentation AMP is used for the input of XLR balance signal. Output goes through Aurora-AMP module,which has high precision with balanced transfer circuit, allowing well balanced transmission of the signals. It requires a total of 4 modules in order to accomplish a completely balanced architecture including AMP and volume control for L/R channels. In addition, attenuation level in the HOT and COLD circuits, frequency responses, distortion must be identical in each channel. Otherwise, the differences will surface in the output stage. On the other hand,there are substantial merits such as immune to external noises and cable length. For these reasons, PREDA adopted balanced structure.

Input control module

5.Balanced Input has Instrumentation Amp Structure

-TBSP

True Balanced Signal Path

PREDA-TBSP is high grade version of PREDA, this is true balanced signal path. From input, amplification, autoformer attenuator, output buffer to output, all of signal path are true balanced configurations. This is almost double complexity of total circuitry compared to standard PREDA. This TBSP system can eliminate common mode noise and get rid of ground noise influence, then make pure music signal and information transportation from source to power amplifier. Power supply unit is separate chassis. Four units of power transformer and regulators are completely independent for left/right channel and analog/digital control section. PREDA-TBSP is non compromise control center for real balanced signal path audio system. All functions are remote controlled by hand set.